Mucus-producing adenopapillary (non-epidermoid) carcinoma of the parotid gland

Abstract

In a histologic reexamination and reclassification of a series of 1,678 tumors of the parotid gland, 47 (2.8%) exhibited structures characteristic of mucusproducing adenopapillary (non-epidermoid) carcinoma. There seems to be a rather close relationship between this tumor type and mucoepidermoid carcinoma. The differential diagnostic difficulties between these two groups can perhaps explain why in earlier works the groups of mucus-producing adenopapillary carcinoma are so small and mostly contain only occasional cases. Our strict criterion of mucoepidermoid carcinoma, demanding the demonstration of squamous differentiation, separates these tumors from mucus-producing adenopapillary (non-epidermoid) carcinomas. This can explain why the group of mucoepidermoid carcinomas comprised 3.7% in our series as compared to 4–12% in other works. Histologically, we have divided the 47 tumors into two subgroups: one consisting of 28 invasive growing tumors (high-grade malignant) and one of 19 non-invasive growing tumors (low-grade malignant). The high-grade malignancies have a poor prognosis with a determinate survival rate similar to adenoid cystic carcinoma, and the prognosis of the low-grade type is comparable to that of low-grade mucoepidermoid carcinoma. In order to improve the poor prognosis in the high-grade mucus-producing adenopapillary carcinoma, the authors recommend that parotidectomy should be routinely combined with radical neck dissection.